Biscationic monoazo dyes for acid-modified nylon

ABSTRACT

Red to rubine biscationic monoazo dyes having the formula   WHEREIN R1 and R2 H, alkyl or phenyl R3 alkyl or benzyl R4 H, alkyl, alkoxy, Cl, NHCO alkyl or NHCOC6H5 R5 Cl, alkyl or alkoxy WHEREIN R6 alkyl R7 alkyl or hydroxyalkyl R8 alkyl, hydroxyalkyl or benzyl or R7 and R8 together are piperidino or pyrrolidino R6, R7 and R8 together or pyridinium A is anion and ALKYL ONE TO FOUR CARBON ATOMS ARE USEFUL FOR DYEING NYLON STYLING YARNS, HAVE BRIGHT SHADES WITH GOOD BUILDUP AND LIGHTFASTNESS ON ACID-MODIFIED NYLON WITH NEGLIGIBLE AFFINITY FOR UNMODIFIED NYLONS WHEN DYED THEREON AT A PH of from about 6 to about 6.5.   WHEREIN N O or 1 Z H when n O Z OH when n 1

United States Patent James [54] BISCATIONIC MONOAZO DYES FORACID-MODIFIED NYLON [72] Inventor: Daniel Shaw James, Hockessin, Del.

[73] Assignee: E. I. du Pont de Nemours and Company,

Wilmington, Del.

[22] Filed: July 27, 1970 [21] Appl. No.: 58,706

[52] US. Cl ..8/4l B, 260/154, 260/157 [58] Field olSearch ..8/41 A,4lB; 260/154, 157

[56] References Cited UNITED STATES PATENTS 3,078,137 2/1963 Bavmann etal. ..8/57 3,338,660 8/1967 Biedermann ....8/54 3,389,549 6/1968 David..57/140 Primary Examiner-George F. Lesmes Assistant ExaminerM. B.Wittenberg AttomeyMichael J. Bradley ABSTRACT Red to rubine biscationicmonoazo dyes having the formula R l I R e/ 1 a wherein R and R H, alkylor phenyl V Rfi lekyleie Mar. 14, 1972 R alkyl or benzyl R.,=H, alkyl,alkoxy, Cl. NHCO alkyl or NHCOC Hr,

alkyl 1-4 carbon atoms are useful for dyeing nylon styling yarns, havebright shades I with good buildup and lightfastness on acid-modifiednylon with negligible affinity for unmodified nylons when dyed thereonat a pH of from about 6 to about 6.5.

4 Claims, No Drawings BISCATIONIC MONOAZO DYES FOR ACID-MODIFIED NYLONBACKGROUND OF THE INVENTION Multicolored bulked continuous filament BCFnylon styling carpeting has grown rapidly in popularity since itsintroduction a few years ago. Such carpeting initially contained severalpolyamide modifications which differ from each other with respect to theconcentration of free amine end groups in the fiber (e.g. U.S. Pat. No.3,078,248 describes the preparation of polyamide fibers of varying amineend content). Since amine groups act as dye sites for acid dyes, thesemodified nylons vary in acid dye receptivity. Hence, when a carpetcomposed of three such nylons having low, medium and high amine endcontent (which may be termed light-, mediumand deep-dyeable nylon,respectively) is dyed with a suitable acid dye or dyes, a three-toneeffect is produced. Greater versatility of shade is obtainable by usingdisperse dyes in addition to acid dyes. Disperse dyes are notsite-dyeing (since they possess no ionic groups) and thus dye all nylonmodifications of the kind described above to the same depth,irrespective of the amine-end concentration. To illustrate this point,one can visualize a tricomponent nylon carpet dyed first with a suitablered acid dye and then with a yellow disperse dye. The red dye willproduce light, medium and deep red shades, respectively, on the threedifferent kinds of nylon. The yellow disperse dye, however, will dye allthree nylons to the same depth of shade. The resulting shades will bereddish-yellow, orange and scarlet, respectively.

With the introduction ofacid-modified nylons (eg as in US. Pat. No.3,184,436), the range of multicolored effects obtainable on BCF nylonstyling carpeting was greatly increased. Acid-modified nylons, whichcontain sulfonic acid groups on the polymer chain, are dyeable withcationic dyes but have little or no affinity for acid dyes. Thus, acarpet containing two or three nylons of varying affinity for acid dyesand an acid-modified nylon which reserves (is not stained by) acid dyescan be dyed at will with any combination of shades, including primarycolors (those colors that cannot be obtained by combining other colors)side by side on the same carpet. Dyeing methods have been developed sothat such carpets can be dyed with acid and cationic dyes in a singledyeing operation. Thus, a blue acid dye and a red cationic dye (with asuitable dyebath additive to prevent coprecipitation of the dyes) willproduce varying shades of blue on the acid dye-receptive nylons and ared shade on the acid-modified cationic dyereceptive nylon.

The choice of cationic dyes for acid-modified nylon in styling carpetingdepends on two main considerations, namely, an adequate degree offastness (particularly to light) on the acidmodified nylon and a lack ofcross-staining on the unmodified nylons. The former consideration isself-explanatory, since the fastness requirements for carpet dyes arehigher than for almost any other dye end-use; the latter considerationis important since cross-stains can have poor fastness properties andwould tend to dull the shade of the acid dyes on the unmodified nyloncomponents and minimize the color contrast between the different typesof fiber.

It has been found that the staining of unmodified nylon with cationicdyes depends on the pH at which the dyes are applied to the substrate.Many commercial, monocationic dyes have satisfactory nonstainingcharacteristics on unmodified nylon at low pH (i.e. 4 or below).However, at the preferred dyeing pH range, for cationic dyes, of 6-6.5,staining becomes more apparent and, in most cases, is unacceptable forcommercial SUMMARY OF THE INVENTION Nylon styling yarns containingacid-modified nylon and unmodified nylon yarns can be dyed in an aqueousdyebath at a pH of from about 6 to about 6.5 with red to whinebiscationic monoazo dyes having the formula wherein R and R H, alkyl orphenyl R alkyl or benzyl R H, alkyl, alkoxy, Cl, NHCO alkyl or NHCOC H RH, Cl, alkyl or alkoxy R alkyl R alkyl or hydroxyalkyl R alkyl,hydroxyalkyl or benzyl or R and R together or pyridinium A is anion andalkyl one to four carbon atoms The dyes have excellent reserve ofnonacid-modified nylon, deep dyeing characteristics on acid-modifiednylon and excel- 0 lent exhaust from the dyebath.

DESCRIPTION OF THE INVENTION The dyes useful in this invention may beprepared by diazotizing an amine of the formula IL NH,

(where R, and R are as defined above) in aqueous hydrochloric orsulfuric acid at about 0-15 by addition of sodium nitrite. The diazoniumsalt is then coupled to an amine of the structure (where the symbols areas defined above) by adding the diazonium salt to an aqueous solution ofthe coupler, or vice versa, or by simply adding the pure coupler to thediazonium salt preparation. Coupling may be effected at room temperatureor below, but preferably at 50-20 C. The coupling reaction may beaccelerated by raising the pH to about 3-5 with a suitable inorganicsalt or base, such as an alkali metal acetate, bicarbonate, carbonate orhydroxide. Sodium acetate and sodium hydroxide are the preferredreagents, for economic reasons. Carbonates and bicarbonates are lesssuitable because of foaming caused by evolution of carbon dioxide.

Finally, the desired dye is produced by quatemization of theintermediate azo dye with any suitable quaternizing agent. Examples arealkyl chlorides, bromides or iodides; alkyl sulfates; benzyl chloride,bromide or sulfate and alkyl or benzyl ptoluenesulfonates. Alkylradicals may contain up to four carbon atoms, but are preferably methylor ethyl.

Alternatively, the diazonium salts described above may be coupled to theunquaternized form of the couplers, i.e. to compounds of the formula 1alkyl omomoHm-w where W NR or NHCOCH,NR-,R the other symbols are asdefined above.

Coupling may be effected as described above, the coupler either beingdissolved in water by adding sufficient acid to protonate the pendanttertiary amine, or being added directly to the diazonium saltpreparation. Subsequent quaternization produces the desired biscationicdyes.

The nature of the anion A does not affect the excellent application andfastness properties of the subject dyes. The reasons for using one anionin preference to another are (a) economics and (b) ease and completenessof isolation of the dye. Anions may be introduced in various ways, forinstance, in the acid used to perform the diazotization and couplingreactions (almost always hydrochloric acid), in the salt used toaccelerate the coupling reaction, in the quaternizing agent (examples ofwhich are given above) and in the salt used to precipitate the dye fromsolution prior to isolation. Possible salting agents include sodiumchloride, sodium iodide, sodium fluoborate and zinc chloride.Arylsulfonates may also be used if low water solubility is required.

Examples of imidazoles that may be used to prepare dyes of Methods ofpreparation of substituted Z-aminoimidazoles such as those appearing inTable l are known in the art.

For example, the preparation of 4-(or 5-)meth yl 2- aminoimidazole byheating guanidine and propargyl bromide together in ethanol is disclosedin Japanese Pat. No. 24,385 (1963). The synthesis of4,5-diphenyl-Z-aminoimidazole and other derivatives, by heating aromatica-hydroxyketones (benzoins) with l,Z-hydrazinedicarboxamidine inaqueousethanolic sodium hydroxide and reducing the resulting azointermediates by catalytic hydrogenation to the desired products, isdisclosed by A. Kreutzberger in J.O.C. 27 (1962) pp. 886-891. Thepreparation of 4,5-dimethyland 4-inethyl- S-phenyl-Z-aminoimidazoles andother derivatives, by reacting oz-aminoketones with cyanamide in hotwater at pH 4.5, is described by Lancini et al., J. Heterocyclic Chem, 3(I966) pp. 152-4.

The couplers containing a pendant tertiary or quaternized amine groupmay be prepared by methods known in the art. For example, N-alkylanilines, optionally substituted in the 2- and/or S-positions, may be il. reacted with ethylene oxide, giving the N-(B-hydroxyethyl)derivatives. Replacement of the hydroxyl group with a halogen atom andsubsequent addition of a secondary or tertiary amine gives pendanttertiary amine or quaternary ammonium salts, respectively, reactedsequentially with ethyleneimine, chloroacetyl chloride and a secondaryor tertiary amine, giving pendant tertiary amine or quaternary ammoniumsalts, respectively, reacted sequentially with epichlorohydrin and asecondary or tertiary amine, or, 4. reacted with epichlorohydrin, thenwith ammonia to replace the terminal chlorine with a primary aminegroup, and then sequentially with chloroacetyl chloride and a secondaryor tertiary amine.

Other useful couplers may be prepared by condensing chlorobenzene,optionally substituted in the 2- and/or 5-position 5, with piperazineand alkylating or quaternizing with an alkyl halide or sulfate. Examplesof couplers that are useful for preparing dyes of this invention aregiven in Table 2.

The biscationic monoazo dyes of this invention have been found to havegood exhaust and lightfastness on acid-modified BCF nylon fibers. Suchpolymers are described, for instance, in U.S. Pat. No. 3,184,436 andcontain sulfonate groups along the polymer chain which act as dye sitesfor basic or cationic dyes. The instant dyes have also been found todisplay an almost total lack of affinity for unmodified nylon fibersunder neutral to weakly acidic conditions. In other words, at pH 6-6.5,the biscationic dyes almost completely reserve nylon fibers which do notcontain sulfonate groups. This behavior differs from that of known redmonocationic azo dyes, which tend to stain unmodified nylon undernear-neutral conditions and which display good reserve only under moreacidic conditions (i.e. pH 4 or below).

The importance of these observations lies in the fact that nylon stylingcarpeting, which contains acid-modified and unmodified nylons, ispiece-dyed most satisfactorily at pH 6-6.5. Acid and cationic dyes areapplied to the carpeting from a single dyebath, which contains anadditive to prevent coprecipitation of the oppositely charged dyemolecules. There are several reasons why neutral to weakly acidicconditions are preferred for this dyeing procedure.

a. Although cationic dyes generally reserve unmodified nylons moreefficiently at lower pH, they do not exhaust as well from the dyebathonto acid-modified nylon.

b. Acid dyes generally exhaust more efficiently at lower pH, but suffera decrease in levelness on unmodified nylon and tend to stainacid-modified nylon.

c. Styling carpet that has a jute backing undergoes increased stainingof the nylon by impurities in the jute with increasing acidity, causingdulling of dye shade and deterioration of dye fastness properties.

At neutral to weakly acidic conditions, cationic dyes may be applied tonylon styling carpet in conjunction with neutraldyeing acid dyes, whichhave satisfactory exhaust and levelness under these conditions. It hasnow been discovered that the biscationic dyes described herein abovehave significantly better nonstaining properties on unmodified nylon atpH 6-6.5 than any known commercial red cationic dye.

Although biscationic dyes have been disclosed in the patent literaturefor several years for use on various substrates, particularly foracid-modified acrylic fibers, biscationic monoazo dyes like thosedisclosed in the present invention were found to have very limitedutility on acrylics (such as those disclosed in U.S. Pat. No. 2,837,500and U.S. Pat. No. 2,837,501) because of low affinity and poor buildup onthe substrates. Much the same thing was found to be true ofacid-modified polyester (such as is disclosed in U.S. Pat. No.3,018,272). Thus, it was totally unexpected to find that the biscationicdyes of this invention have entirely adequate buildup on acidmodifiednylon, producing deep red to rubine shades thereon.

Commercial nylon styling carpet usually contains acidmodified nylon andfrom two to four unmodified nylons of varying acid dye receptivity whichare tufted onto a backing in a random pattern to give the desiredstyling effects.

In order to evaluate cationic and acid dyes for this end-use, however, atest carpeting is used in which the various nylons are tufted onto abacking in discreet bands. The instant dyes were evaluated on a testcarpet with the following specifications: five bands of trilobal,jet-bulked BCF nylon yarns, spun from the nylon flake, are tufted onto anonwoven polypropylene backing, each band being six tufts in width. Thefirst band is acid-modified, 1,300 denier BCF nylon (such as thatdescribed in U.S. Pat. No. 3,184,436). The other four bands areunmodified, 3,700 denier BCF nylons which have progressively increasingacid dye receptivity by virtue of an increasing amine-end content, whichranges from 5 to more than 100 gram-equivalents of free amine ends per10 grams of polymer. The specific amine-end range for each band is asfollows:

1. 5-25 gram-equivalents: light-dyeable" with acid dyes 2. 25-55gram-equivalents: medium-dyeable with acid dyes 3. 55-100gram-equivalents: deep-dyeable" with acid dyes 4. 100-120gram-equivalents: ultradeep-dyeable" with acid dyes The deep-dyeingnylons (3) and (4) are disclosed in U.S. Pat. No. 3,078,248.

The carpeting is dyed by the procedure used for commercial stylingcarpet, which can be dyed with acid and cationic dyes in the samedyebath by using as a dyeing assistant a sulfobetaine of the generalstructure CH2CH20) CHzCHzOH n-omN-cmomomsos onzoflzm omomofl where Raliphatic hydrocarbon radical of 7-17 carbon atoms (m+p) 4 Thepreparation of these compounds is described in U.S. Pat. No. 3,280,179.Their utility in this particular end-use is disclosed in the defensivepublication dated 4-29-69, of Robbins, Ser. No. 634,477. The functionsof the sulfobetaine additive are to prevent coprecipitation of the acidand cationic dyes, to enhance the levelness of both classes of dyewithout suppressing buildup and to minimize cross-staining.

Piece dyeing is carried out at temperatures above 70" C. and preferablynear the boil (-100 C.). Lower temperatures cause inferior exhaust andpoor contrast through cross-staining. The pH of the dyebath may beanywhere from 3 to 9, but

the most favored pH range is 6-6.5, for reasons given earlier in thediscussion.

The sulfobetaine dyeing assistant may be used in amounts as low as 0.05%of the weight of the fiber being dyed, but the best results are obtainedwith 02-03%. Amounts in excess of 0.5% of the weight of the fiber haveled to an increase in crossstaining.

The dyeing procedure is advantageously preceded by a bleach scour, asdescribed in Example 80, in order to obtain maximum shade brightness andcontrast.

Finally, dyeing is usually followed by conventional rinse and dryingsteps. Conventional fishing, drying, latexing, and double backingapplication may be performed by customary means.

The aforementioned dyeing procedure may be adapted for the continuousdyeing of styling carpet, a comparatively new technique which isreferred to in Melliand Textilberichte, 48, 415-448 (Apr., 1967).Continuous dyeing is taught as being related to piece dyeing in that isis an aqueous process, but

a. at very low bath ratios, i.e., :1 instead of 30:1 to 50:1,

and

b. the rate of fixation is much faster, since temperatures near the boilare attained more quickly in a steamer than in heating up a beck.Cationic and acid or direct dyes may also be printed onto nylon stylingcarpeting, with excellent results.

Although the discussion has been devoted up to this point to stylingcarpeting, there are other areas in which BCF nylon styling yarns may beeffectively used, such as upholstery and accent or throw rugs. The dyedacid-modified nylon of this invention would be applicable to theseend-uses as well as for carpeting. The dyeing of these items may becarried out by the same means as that described for carpeting, usingsuitable equipment. Thus, carpeting is usually dyed in becks; upholsteryis usually dyed in jigs; accent or throw rugs are usually dyed in paddlemachines.

Evaluation of the instant dyes was carried out by dyeing them singlyonto nylon test carpeting as described above, in the absence of any aciddyes. In this way, the degree of crossstaining on the unmodified nylonsis readily apparent. Staining occurs most readily on the unmodified bandcontaining the least number of free amine ends, since this nyloncontains the highest density of carboxylic acid end groups, which canact as dye sites for cationic dyes. Staining by cationic dyes can beinduced on the deep-dyeable" and ultradeep-dyeable nylons by raising thedyeing pH, or by suitable choice of dye. However, the staining of thelight-dyeable and medium-dyeable bands would then be so bad as to bequite unacceptable. A reasonable candidate will barely stain the firstband and will leave the higher amine-end nylons untouched. Example 1 1iilustrates some typical results achieved by the instant dyes andcompares them with a structurally related, monocationic dye and acommercially available monocationic red azo dye.

The preparation of the dyes of this invention may be illustrated by thefollowing examples. Parts are given by weight.

EXAMPLE 1 was maintained at 3.5-4 during the coupling reaction byaddition of 30% sodium hydroxide solution. The mixture was then allowedto warm up to room temperature while stirring over a period of2 hours.It was then warmed to 35 C. and 38.5 parts of sodium iodide weregradually added. An oily substance was precipitated, which crystallizedon stirring overnight. The

crystals were isolated by filtration and reslurried in isopropanol.Filtration yielded the solids, which were washed with isopropanol andreslurried in 5% sodium iodide solution. The material was reisolated byfiltration, washed with 5% sodium iodide and then with isopropanol, anddried. Yield: 19 g. The material had an absorptivity of 63.2 liters gramcm? at 457 y. (in dimethylacetamidawater 4:1). The structure of theintermediate is b. A mixture of 15 parts of the intermediate from (a)above 200 parts of isopropanol, 30 parts of methyl iodide and 9.4 partsof anhydrous sodium carbonate were heated to the reflux temperature for6 hours. The reaction mixture was allowed to cool to room temperature bystirring overnight. The solids were isolated by filtration, washed withisopropanol, reslurried in 10% sodium iodide solution, reisolated byfiltration, washed with 10% sodium iodide and then with isopropanol anddried. The dye had an absorptivity of 71.8 liters gram cm. at 515 ,u.

Found: C, 38.4, 38.0; H, 5.8, 5.7; total N, 13.3, 13.2; Azo N, 4.5, 4.5.Calcd. for C H I N C, 39.2; H, 5.6; total N, 13.7; Azo N, 4.6. Thestructure of the dye is EXAMPLE 2 a. 12.5 Parts of bis(Z-aminoimidazolium )sulfate were diazotized in the manner described inExample 1 and added over a .-hour period to a solution of 24 parts of[2-(N-ethy1- anilino)ethyl]trimethylammonium chloride in 60 parts ofwater which had been precooled to 5-10 C. The pH was maintained at 44.5by addition of sodium acetate. After stirring for 1 hour at 5-10 C., thereaction mixture was allowed to warm-up to room temperature withstirring. It was then heated to 40-45 C. and treated with 36 parts ofsodium iodide. The product precipitated from solution. After stirringthe reaction mass overnight at room temperature, the solids wereisolated by filtration and reslurried in turn in isopropanol and then in5% sodium iodide solution, as described in Example 1(a). Afterisolating, washing with 5% sodium iodide and isopropanol and drying, 21parts of product were obtained, having an absorptivity of 56.6 litersgram 1 cm. at 450 a. The structure of the intermediate is b. A mixtureof 20 parts of the intermediate from (a) above, 15.2 parts of methyliodide, 5.7 parts of anhydrous sodium carbonate and parts of isopropanolwas heated to the reflux temperature for 10 hours. After allowing thereaction mixture to cool to room temperature, the solids were isolatedby filtration. They were washed with isopropanol, reslurried in zHs 6B21 C 2 4 0 a):

a. 12.5 Parts of bis(2-aminoimidazolium)sulfate were diazotized andcoupled to 23 parts of N-ethyl-N-[2-(N,N-diethylamino)ethyl]-m-toluidine in the manner described in Example la.Yield: 38.7 parts, having an absorptivity of 46.8 liters gram cm. at 465p The structure of the intermediate T N\ /C 211 N=N N 2 9 e N l C 2114 12 5) 2 b. Quaternlzation of 22.5 parts of the intermediate of (a) abovewith methyl iodide was carried out by the procedure described in Examplelb. Yield: 19.6 parts, having an absorptivity of 77.5 liters gram cm. at525 }L.

Found: C, 40.7, 40.8; H, 5.9, 5.8; total N, 13.4, 13.4; Azo N, 4.7, 4.9.Calcd. for cg HaslgNs: C, 40.3; H, 5.8; total N, 13.4; Azo N, 4.5.

The structure ofthe dye is o 6H $11, a

EXAMPLE 4 a. 12.5 Parts of bis(2-aminoimidazolium )sulfate werediazotized and coupled to 26 parts of N-ethyl-N-[3-(N,N-diethyl-amine)-2-hydroxypropyl]-m-toluidine by the procedure describedin Example In. Yield: 38.9 parts, having an absorptivity of 59.9 litersgram cm. at 472 p. The structure of the intermediate is b.Quaternization of 22.5 parts of the intermediate from (a) above withmethyl iodide, by the procedure of Example lb, yielded 24.7 parts of adark red solid having an absorptivity of 77.0 liters gram cm. at 537 u.

Found: C, 39.6, 39.3;H, 5.5, 5.9; total N, 12.4, 12.3;Azo N, 4.3, 4.4.Calcd. for C H l N z C, 40.4; H, 5.9; total N, 12.8; Azo N, 4.3.

The structure of the dye is EXAMPLE 5 5.3 Parts of his(Z-aminoimidazolium)sulfate were diazotized and coupled to 12.8 parts of[Z-(N-ethyl-mtoluidino)-ethylcarbamoylmethylltrimethylammonium chloridein the manner of Example la, and then quaternized with methyl iodide inthe manner of Example lb. 17.4 Parts of an olive-green powder wereobtained, having an absorptivity of78.3 liters gram cm. at 536 11..

Found: C, 39.9, 39.5; H, 5.2, 5.7; N, 15.0, 14.9. Calcd. for C H IN C,38.5; H, 5.3; N, 15.0.

The structure of the dye is EXAMPLE 6 a. 10.6 Parts ofZ-aminoimidazolium sulfate were diazotized by the procedure of Example10. The diazonium salt was added over a period of l5-20 minutes to asolution of 25.4 parts of N-phenyl-N, N'-dimethylpiperazinium (preparedby heating N-phenylpiperazine with excess methyl iodide and sodiumcarbonate in isopropanol) in 150 parts of water and 12 parts ofION-hydrochloric acid which had been precooled to 10 C. Sodium carbonatewas added during the coupling procedure to maintain the pH at about 2.The reaction mixture was stirred for 2 hours at 10 C. and then allowedto warm up to room temperature. The pH was adjusted to 44.5 with sodiumhydroxide solution and parts of sodium iodide were added. The mixturewas stirred overnight and the solids were isolated by filtration. Theorange-brown solids were washed with 5% aqueous sodium iodide and then 5with isopropanol and dried. The dye had an absorptivity of 49.6 litersgram cm. at 403 Based on the above procedure, the structure of the dyeis iodide EXAMPLE 7 The dyebath was adjusted to pH 6 with monosodiumphosphate and the temperature raised to 80 F. for 10 minutes. 0.05 Partof the dye of Example 1 was added and. after holding the dyebath at 80F. for 10 minutes, the temperature was raised at ca. 2 F. per minute to210 F. and held at this temperature for 1 hour. The carpeting was rinsedin cold water and dried. The acid-modified band was dyed a deep redshade. The unmodified bands were negligibly stained.

To Prepare Z-lmidazolium Sulfate To a slurry of 200 parts ofS-methylisothiourea sulfate in 350 parts of water was added 2!2 parts ofaminoacetaldehyde diethyl acetal. The flask was fitted with an aircondenser. which was topped by a tube leading to a trap cooled in dryiceacetone to catch the methyl mercaptan evolved. The reaction flask wasgently warmed on the steam bath such that. CH SH evolution remainedunder control. EXAMPLE 9 After the gas evolution abated (=-25 min.), themixture was heated on the steam bath for an additional 15 minutes,cooled, and concentrated to a viscous oil under partial vacuum. This oilwas taken up in 160 parts of methanol and treated with acetone to give230 parts of product as fluffy l5 colorless crystals. m.p. l50l 52 C.The mother liquors were concentrated to a viscous oil, taken up inmethanol and again Printing of BCF Nylon Styling Carpeting A sample ofnylon styling carpeting containing acidmodified, rnedium-dyeable andultradeep-dyeable nylons tufted in a random pattern on a nonwovenpolypropylene backing was printed with a mixture containing the cationicdye of Example 2 5 parts treated with acetone to glve a second crop of94 parts for a he sulmbmmc described in Example 8 05 pm total of 324parts (91%) of N-( 2.2-dlethoxyethyl)guanldlnlum glacial acetic acid 5parts u]fate carrageenin thickener to give the desired viscosity A flaskfitted with an air condenser and containing 100 parts ofN'(2,2-diethoxyethyl)guanidinium sulfate and 61 parts of 37%hydrochloric acid was heated vigorously on a steam bath for 15 minuteswith occasional swirling. Without cooling the mixture. 250 parts ofwater were added and the resulting solution concentrated in vacuo to aviscous oil. This was taken up in 250 parts of water, concentrated to anoily crystalline mass, taken up in 45 parts of absolute ethanol and Thecarpeting was steamed at 212-220 F. for 10 minutes, rinsed, scoured for15 minutes at 160 F. in a 0.03% aqueous solution of the condensationproduct of 20 moles of ethylene oxide with 1 mole of C alcohol. rinsedand dried. The acidmodified nylon fibers were dyed a deep red shade. Theunmodified fibers had a negligible stain.

treated with dry acetone to give 27.5 parts of 2- 3O EXAMPLE 0aminoimidazolium sulfate.

The mother liquor and acetone washings were concentrated ContinuousDyeing of Nylon styling Carpefing to dryness taken up in 37 parts of 37%hydrochloric acid, Using Kusters Equipment as described in TextileChemist 'heated for 15 minutes on the steam bath, and the workup and1970- PP- 6-12, nylon Styling carpeting procedure repeated to give 16.4parts of product for a total of 5 as descnbfd m f lp 8 above was runthrough 3 43.9 parts (75%) of Z-aminoimidazolium sulfate, m.p. 270 C.bath at 80 comammg (dec.).

The following examples illustrate the dyeing methods for 'mhdexlendedwill W Wide B- a sull'aled polyglyco! ether 0.6 g.ll.

banded test carpet prepared as described on pages 15-16 above. In orderto demonstrate the reserve of the biscationic 4O dyes on unmodifiednylon, they were dyed in the absence of acid dyes onto the banded nyloncarpeting.

Pickup was about 80%. The carpeting was then continuously treated withan aqueous dyebath composition containing the dye of Example 3 5 3.11.an organic alcohol extended with EXAMPLE 8 ethylene oxide 0.25 g./l.

. a sulfated polyglycol ether 1.25 gJl.

Dyelng of Banded BCF Nylon Carpenng a urified natural gum ether 2 3.".

a. Bleach Scour the sultobetaine described in Example 8 s gJl.

100 Parts of the banded carpeting described above were f 3 .11.

heated for 5 minutes at 80 F in 4,000 parts of water containphmphae 5ing The dyebath temperature was 80' F. Pickup was about 200%. Thecarpeting was then run through a steamer at 212 sodium perborate 4 partsmsodium phosphate pan F., m whlch the dwell tlme was 8 minutes. Thecarpeting was a sulfobetaine P rinsed thoroughly and dried. Theacid-modified nylon fibers were dyed a deep bluish-red shade; theunmodified fibers were negligibly stained. CH OEzOH R CH2cH2CHzB0a9EXAMPLE 1 l CH2CH2OH Evaluation of Cross-Staining Samples of bandednylon carpeting were dyed, according to the procedure described inExample 8, with where R= a. the dyes of Examples 1-6,

C; alkyl (=30%) b. a monocationic azo dye of the structure C alkyl(-30%) CH C, monounsaturated =40% 1 a The temperature was raised to 160F. for 15 minutes and the N e o mm): I carpet rinsed ln water at 100 F.b. Dyeing Procedure H The carpeting was added to 4,000 parts of watercontaining HI 3 (I) the aforementioned sull'obetaine l part and :lfl 015part c. a commercially available red, CI. 11085 (C1. Basic Redtetrasodium pyrophosphate P l 8) having The structure 01 wherein /C2H5 Rand R H, alkyl or phenyl O2N N:N N (11) R alkyl or benzyl g R H, alkyl,alkoxy, Cl, NHCO alkyl or NHCOC H 5 R =H, Cl, alkyl or alkoxy Thestrength of the dyeings was equivalent to 0.1% of the crude dye byweight on the acid-modified band of the test carpet. alkyl The resultsare given in Table 37 lz or Table 3 CH2CIJH(CH2)D Y$ Light-fastness on ZStainingon acid-modified -'lighl nylon (80 hours Shade on aciddyeablexenon arc fade Dye modified nylon nylon (meter) wherem n 0 or 1 Examplelib) red 5-4 4W 2: H when n 0 Example 2(b).... red 5-4 4 BLW Z: Hwhenn=lExample 3(b). bluish-red 5-4 5-4 Bl. W 0 Example Mb)v rubine 5-4 5Example 5.... bluish-red 5-4 4W e Example 6. reddishorange 5-4 3w. ZBr.D or NHCOCHZNR'ER, I bluish-red 2 5-4Y.W

i red 3 3W.VMD

The numbers given in Table 3 correspond to the Gray Scale whereinratings given 111 the Manual of the American Association of R6=alkylTextile Chemists and Colorists and have the following sig- R7: alkyl orhydroxyalkyl mficance- R, alkyl, hydroxyalkyl or benzyl or 5 negugibie rno change (or stain) R and R together are piperidino or pyrrolidino 4ight ch ng r mini 3 R R and R together are pyridinium 3 noticeablechange (or stain) A is anion and 2 considerable change (or stain) l muchchange (or min) a1kyl= one to four carbon atoms Mu" at a pH offrom about6 to about 6.5.

w weaker 2. The improved process of claim 1 in which R H, R H, Brbrowner R3 CH3, R4 H, R5 H and D duller VMD very much duller Y yellowerCZHE The preceding representative examples may be varied X =N within thescope of the present total specification disclosure, as understood andpracticed by one skilled in the art, to achieve essentially the sameresults. I I

The foregoin g detaile d description has been given for 'ia'r- TheImproved process of 1 m whlch R1 R2 ness of understanding only and nounnecessary limitations are R3 R4 R5 H and to be understood therefrom.The invention is not limited to the exact details shown and describedfor obvious modifications will occur to those skilled in the art. 2 5

The embodiments of the invention in which an exclusive x =N property orprivilege is claimed are defined as follows. \czmgwzmh 1. In a processfor dyeing nylon styling yarns comprising contacting said yarns with adye dispersed in an aqueous H3 dyebath having a pH of from 3 to 9, theimprovement comprising using a biscationic monoazo dye having theformula The improved process of claim 1 in which R H R2 H PO-lOSO W69UNITED STATES PATENT OFFICE CERTIFICATE OF CORREETTON Patent No. 5 '9aDated March 1972 lnv Daniel Shaw James It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

FColumn 2, line 57, the word "nonacid-modified",insert a hyphen to readnon-acid-modified Column 8, lines 7, 28 and 9, the symbol ",u" should bem, Column 9, lines 5, 26, 0, 60 and 75, the symbol should be m M Column10, lines 21, 52 and 6A, the s mbohg/ should be III/4 Claim 1, line 51,the term "A should be A v Signed and sealed this 10th day of October1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GOTTSCHALK Commissionerof Patents

2. The improved process of claim 1 in which R1 H, R2 H, R3 CH3, R4 H, R5H and
 3. The improved process of claim 1 in which R1 H, R2 H, R3 CH3, R4CH3, R5 H and
 4. The improved process of claim 1 in which R1 H, R2 H, R3CH3, R4 CH3, R5 H and